Could be wiring.

It can't fuel properly if IAT / MAF not working.

 

Patterson: Leaks in your X-Type's airbox won't cause MAF and IAT errors. But fix the leaks anyway to keep road grit out of the engine intake.

Our X-Types, like many cars, have an IAT sensor inside the MAF sensor. So your MAF & IAT errors are probably: (1) a bad MAF sensor, (2) a loose or damaged electrical connector to the MAF sensor, or (3) as JagV8 says, damage to the MAF sensor wires.

These pic's show the IAT sensor inside the MAF sensor.
Source: https://howtune.com/articles/162-cle...da3#chunk-4926

 

Thanks fellas, I bought and put in a new MAF sensor today and cleared the codes. I rev'd pass 3,000 RPMs for the first time in a month! Felt good, I'll see if this is in fact the final fix of this saga. Car has been down for a good 5 weeks.

 

Well, that didn't last long, but, the MAF codes did not return. Now I have only the two codes for rich in both banks, P0172, 75. Any ideas what could be causing this?

Been reading that it could be the fuel pressure sensor. Could it be the PCV?

I may reinstall my K&N air filter. I took it out and replaced with a regular air filter when I had lean codes about 18months ago.

 

All the usual causes are in the jag codes (in workshop manual / PDF - both free downloads).

Also, Search will get you what others typically found & did.

 

Patterson: Rich conditions in both banks (P0172 - bank 1, P0175 - bank 2) are less common than lean conditions (P0171 - bank 1, P0174 - bank 2). Why? Extra air can leak in many ways, particularly as our X-Type's age, but less so for extra fuel.

If your X-Type drives well other than the P0172 & P0175 error codes, try clearing the codes several times over a few days and see what driving conditions cause them to reappear. Hopefully you'll see a pattern. If no pattern, check for a weak battery.

A rich condition (too little air) can result from a dirty air filter, or a bad MAP air sensor. Also a bad MAF / IAT sensor, but you already replaced that. Back pressure from clogged catalytic converters is another possible cause.

Too much fuel can result from high pressure in the fuel rail (check using your OBD2 sensor AND a pressure gauge), leaking fuel injectors, or bad fuel rail sensors for injector pressure (IP) or temperature (EFT). Also an EVAP solenoid stuck open after you fill the fuel tank - it's on the fire wall, below the electrical connectors for the bank 1 oxygen sensors.

Other bad sensors can 'confuse' the ECM, causing rich conditions: throttle position (TP) and coolant temperature (ECT).

Here are several threads and links of people working thru these P0172/P0175 error codes, and a good explanation of how fuel trims adjust for lean & rich conditions. The common theme is that it's a process of elimination, which takes time and persistence to troubleshoot. Let us know what you discover.

https://www.jaguarforums.com/forum/s...-p0175-149649/

http://www.jagrepair.com/images/Auto...r%20Rev2-1.pdf

https://www.jaguarforums.com/forum/x...-p0172-106746/

https://repairpal.com/OBD-II-Code-P0172-and-P0175

https://www.jaguarforums.com/forum/x...-codes-192681/

https://www.jaguarforums.com/forum/x...-p0172-110887/

 

I hope everyone is having a peaceful day and observing the Memorial holiday with gratitude, family, friends, and good cheer!

Is the MAP sensor clamped onto the other side of the throttle body, opposite the TPS (throttle position sensor)? I did have to replace the throttle body about 6 years ago with a new one from the dealer. At that time I couldn’t find a new TPS or MAP to just bolt on and see if that would work vs a whole new TB assembly. The TB cost about $1,000 at the time.

The pattern after clearing the codes (72 and 75) has been clear ‘em, then dive to work (18 minute mostly fwy ). At the end of the day, they come back pretty quick as I warm up the car to dive home. By ‘they’ I mean that I have the engine icon lit up and the solid yellow light in the speedo dial.

I am probably killing my cats a little more every time I drive, pushing rich exhaust thru the converters. This barring the small possibility that I’m getting a false rich code from other bad sensors and confusing the ECM, i.e. throttle position (TP) and coolant temperature (ECT), as dwclapp stated above.

They have 150K miles on them, which I imagine under ideal circumstances they could last over 200K miles, but my cats took some damage as un burnt fuel hit them when they were at full temp. as I was stalling out on the fwy last month. This is when I must have had a slow leak in the spark plug well turn into a breach. I had the flashing CEL and the burnt firecrackers smell at the tail pipes.

There is a shop that I trust here that will test for too much back pressure from clogged cats by drilling a hole upstream, and a hole down stream and comparing the pressure difference. I don’t think they have an instrument to check pressure tho, it’s by feel.


Question: Has anyone had luck with putting a spacer at the downstream sensors to possibly pull the sensor head back away from the exhaust stream?

 

Btw, thanks for the links dwclapp. I've been digging thru them. The fuel trims tutorial is very useful.

 

 

Patterson: And a solemn Memorial Day to you as well.

Years ago I was enjoying lunch outdoors in Brussels' central square when an elderly, stooped lady paused her slow walk to ask in French where I was from. When I said "America", she replied softly: "aaahhh, les libérateurs". ~35 years ago still feels like yesterday, and gives perspective to the sacrifices a brave few made for us all.

=========================

The MAP sensor is located on the top, center of the intake manifold, by the firewall. It's not likely the cause of your P0172 & P0175 errors.

The TPS, throttle position sensor is on the side of the throttle body near the PCV hose. It measures the position of the throttle plate. A problem with the TPS can cause P0172 & P0175 errors. FYI, the other side of the throttle body, near the battery, is the servomotor that opens the throttle plate as your foot presses the gas pedal. Ironically 'air pedal' is a more accurate name.

It's possible that when your CEL was flashing, your catalytic converters were damaged by excess fuel and overheating. If exhaust flow is now restricted thru your kitty's cats, this could explain the persistent error codes P0172 & P0175 - rich conditions in both banks when air flow can't keep up with fuel flow.

Since you trust a mechanic to check your catalytic converters for restricted flow, start there. Hopefully the cat's are fine, and you can next test for a bad TPS. Or if you want, test the TPS first - not difficult - then check the catalytic converts for restricted flow.

Spacers for O2 sensors won't fix restricted exhaust flow or a bad TPS.

 

Hey there Mr. dwclapp, considering what you said about the TPS and it measuring the position of the throttle plate, I ordered a TPS and a Torx 5 point bit set so I can R&R it. I recall having a dirty throttle body a few years back; the throttle plate could not close all the way due to grime and dirt accumulation at the edges where the round plate meets with the intake tube. This caused very rough idle, esp. in the mornings when the engine was cold. It would search for a good idle. I cleaned that up with isopropyl alcohol and some cotton swabs, and the result was wonderful, car idled cold and I was done.

What I found today was that the car won't idle. I cleared the codes to drive to work, and along the drive it was okay, but I can tell it's not quite right. I got to work and in neutral I held a rev at 3K RPMs for almost a minute, the engine sounded normal, nice and tight, no misfires or coughing. But, when I let off the 'air pedal' (I like that btw, more accurate than gas pedal) the engine stalled.

On the way home it would not idle at stop lights, just stalled and dies at every traffic light. It starts right up tho, and drives at high RPMs, 4K or so. In 3rd gear at 4K RPMs I let off the accelerator and left it in gear, using the engine to slow down, the revs were fine, no stalling until back at idle.

The new TPS and Torx bits will be here tomorrow. If this doesn't fix it, I may have dirty restricted flow cats that under high revs can be overcome, but at idle there is not enough exhaust pressure to push thru, and so, the engine stalls.

BTW, thanks for the video Dell, but I have already replaced the MAF.

 

New development: Got home today and the car idled for a good 5 mins in the driveway. A few blocks away from home it wouldn't idle, just conked out as it's been doing now for a couple days. I pulled in the driveway just now and let off the pedal and to my surprise, it sat there idling.

Since the no-idle condition started I've been driving to work on the fwy in 4th gear, holding about 4K RPMs all the way, about 15 mins. I've been hoping to blow out clogged cats, but, I know that is a long shot. At this point tho, I've got nothing to lose.

Engine light has not returned since yesterday. It had been returning regularly after a drive, but I've been clearing it everyday, so I know it might be taking longer to re appear, but that let me hold the high RPMs on the fwy.

I must have screwed up on my Amazon order bc the TPS will now arrive June 6th, instead of today, as I thought. The 5 point Torx bits got here tho. Lol.

I'm tempted to go out there and start it up and see if it will idle, but I pulled it into the garage already and shut the door. I'll wait until morning when I drive to work. Thing is, when it's cold in the mornings, it does idle at first, until the choke (or whatever its called now) closes, then it has gone back to stalling out if the accelerator is not pressed a little.

 

One of the consequences of insisting to drive a stalling 5 speed manual, is that, in a parking lot you might drop it in gear to turn the flywheel or whatever, and restart the car as it stalled.

I used to do this when I was 17 with my 1974 Mercury Capri, inline 4 cyl 4 speed. Giver her a push and jump in, pop into 2nd gear please! The rear wheels belched a jolt of confidence, and you were off!

I didn't mean to but maybe it was muscle memory. I just popped the Jag into 2nd while coasting after the engine died.

Only in an emergency to stop people from dying, would I do that with this car. Anyway, the transfer case probably loved the chiropractic adjustment. Haven't heard back...

 

Patterson: Do I understand correctly, that the symptoms now are:
+ at highway speeds: plenty of power and runs smoothly
+ at idle and cold: idles smoothly
+ at idle and warm: stammers and stalls

If 'yes', this sounds more like a vacuum leak causing a lean condition, and not a rich condition or clogged cats.

No CEL, error codes or pending codes? Have you checked the fuel trims at idle and ~2,500 rpm? Let us know if you're unfamiliar with this diagnostic check.

 

Hey there, I haven't checked the fuel trims, just getting familiar with what can be learned from them. I have the Torque Pro app and scanner. Does anyone know how to use this app to get the fuel trim data? I've been thru the menus some, only got the Pro version last night.

The TPS will be here today. Is that just a bolt on part, or does it need to be clocked, or set in some specific way? Does the ECM have to 'learn' the new TPS?

New development: CEL was out until getting home yesterday when it illuminated. I pulled the codes and I got P0306, P1316, misfire in cylinder 6. As I stand in front of the car looking at the engine, cylinder no. 6 is to the right, near the battery, correct? I pulled the airbox and then pulled the coil and plug, all of which are new. Spark plug looked good, no carbon dust or burn marks. I switched coil no. 4 with no. 6. I drove to work today and did not have new codes for the misfire moving over to cylinder 4. So, I just cleared the codes now. Hard to believe there is really a misfire, engine sounds good on hwy, has normal power.

To your points dwclapp,

+ at highway speeds: plenty of power and runs smoothly - YES
+ at idle and cold: idles smoothly - Not smoothly, rough, but does idle
+ at idle and warm: stammers and stalls - YES


I did the carb spray test on the vacuum lines on top of the manifold and found a leak at the one that goes to the EVAP canister. I packed RTV on that one a week ago. The other connection showed no change in idle when I sprayed so i think it's fine, plus that one, going to the brake booster, was replaced about 2 years ago. I could recheck my RTV job to make sure I got the leak plugged.

As I pulled the airbox off yesterday to address the misfire, I peered up the throttle body at the round plate and noticed it was not fully closed. It was open say 5 degrees from totally vertical and closed. Wondering if that could be an issue. I did push it open about 15 to 20 degrees when I cleaned it a week ago.

 

As my boss says here in the engineering lab "There's no fun like troubleshooting!" Lol.

 

You typically can't detect misfires which are bad enough to cause catalyst damage, but the car can.

Read the jag doc and you'll see many codes are 2-trip (as required by your laws).

Clearing codes resets the counter and much else (but will not prevent misfires of course).

 

The misfire has become more apparent in the sound of the reving engine and at idle. Since I've cleared the codes, they've not come back yet, but they will. Waiting for that to see if the misfire moved from 6 to 4.

 

Hello and sorry that I am very confused as for how to post a new message. I am not only a brand new member here but overwhelmed by your (all) wonderful input. As amateur as I am, I am really desperate by the bad faith of the mechanics in the Pennsylvania area where I live which want to convince me that I should give rid of my (scornful grinning) "Jaguar". I don't want to keep a long constitutional speech here but simply to find out what to do with my (at least three) trouble codes after my engine light went on: P1035, C0081, P 0420. When I asked the various mechanics if they can change my oxygen sensors of my Bank 1 (both, S.1 --see C0081, and S2 --see P1035) if I bring them the new ones, they said that a sensor costs $100 and I "obviously" have a catalytic convertor failing, not sensors. Which catalytic converters they said, are FIVE. and what of the 10 sensors I need to change????!!! Dear Patterson, you said that you changed BOTH sensors. Please help me here. How many BOTH I need to change for my Bank 1 problem when the photos shown by SIR only indicate two kinds/pieces? Please forgive my (desperate) ignorance. Thank you.

 

There are only two catalytic converters on the X-Type. One for each bank. And each one has an upper and lower O2 sensor. 5? hhave no idea what your "mechanic" might have been referring to,P0420 is for Bank1. If one of the sensors was bad I would think you would have an additional code for which one is bad. Might also be a code for a misfire(s).

I am not seeing P1035 as a valid Jaguar code. Are you sure that number is correct?